Resistive memory cells, such as resistive random access memory (RRAM) cells, store data by switching between electrical resistance states. For example, for binary data storage, a high-resistance state of the resistive memory cell may be read as logical “1,” while a low-resistance state of the resistive memory cell may be read as logical “0.” Switching between resistance states may be achieved by applying different physical signals (e.g., voltage, current, etc.) across the resistive memory cell to form, at least partially remove, or repair conductive filaments or bridges in a resistive memory element. Forming the conductive filaments can decrease the resistance of the memory cell, removing the conductive filaments can increase the resistance of the memory cell, and repairing the conductive filaments can decrease the resistance of the memory cell once again. Conventionally, the initial formation of the conductive filaments is referred to as “forming,” the at least partial removal of the conductive filaments is referred to as “resetting,” and the repair of the conductive filaments is referred to as “setting.”
An example of an RRAM cell is a conductive bridge random access memory cell. In a conventional conductive bridge random access memory cell, the resistive memory element includes a conductive material (also referred to as an “inert electrode”), an active material, and an ion source material (also referred to as an “active electrode”). The active material may be on the conductive material, and the ion source material may be on the active material. The ion source material includes an active metal, such as copper (Cu), silver (Ag), or zinc (Zn). The conductive filament is formed and/or set by the movement of Cu, Ag, or Zn cations (e.g., by application of a voltage across the ion source material) from the ion source material, through the active material, and to the conductive material, where the Cu, Ag, or Zn cations are electrochemically reduced and deposited until a path of less resistance (i.e., the conductive filament) is formed across the active material. The conductive filament can be reset (e.g., by applying a voltage with reversed polarity across the ion source material) by ionizing and returning the Cu, Ag, or Zn atoms to the ion source material, or can remain in place indefinitely without needing to be electrically refreshed or rewritten.
Unfortunately, internal stresses in the materials (e.g., the ion source material) of conventional resistive memory elements, combined with the characteristics of interfaces between the materials, may cause delamination of adjacent materials. Delamination may, for example, occur during subsequent processing of the resistive memory element or RRAM cell, such as during subsequent thermal anneal processing. If adjacent materials delaminate or detach, successful fabrication of the RRAM cell or the RRAM device may be hindered or precluded and/or the fabricated RRAM cell or RRAM device may exhibit at least one of performance and durability problems.
It would, therefore, be desirable to have a resistive memory element, for example, a resistive memory element of a conductive bridge random access memory cell, exhibiting increased interfacial adhesion (e.g., as-deposited, following subsequent processing, and during normal use and operation) between adjacent materials of the memory element. It would also be desirable if the resistive memory element exhibited improvements in material smoothness and in at least one electrical property.